Great review.
I have 2 of these Mark 7 A, both with the 'big case', solid stainless steel / fat lugs style, and therefore likely part of the batch of these less than 1000 'transitional' watches between the weems and the smaller / plated version
The first one is quite similar to yours (with the exception of hands which are the conventional ones as pictured by Zaf):
The second one is very special. First, it has the 'red 12' dial (same dial as your weems). Secondly, it has the big lugs case, which is stainless steel, but in 3 parts (caseback, case, and a smooth bezel). And lastly, it has a huge crown, same as in the Weems.
Now, the interesting part is that if you remove this smooth bezel, you will see that there is a grove under it around the dial opening, as if it was initially the place for a rotating bezel (as you would expect on the original Weems). Still, it has only one hole for one stem / crown
(sorry, no picture of the watch with the bezel removed):
So, it seems that this watch is even more 'transitional', as it appears that at some point in 1942 they decided that the Weems bezel was not needed anymore, and they have assembled a few watches using original Weems cases and completing them by smooth bezel instead of the Weems one.
I have seen one other identical watch before (also with same red 12 weems dial), so with this one it is at least 2 such transitional watches in existence, but who knows how many they made before creating the normal big case ?
Military watches are definitively interesting for these stories, when you see that design was dictated by actual needs and components availability in real time !
Thank you for this great presentation of the Mk VII A